Solid-state multispark ignition

ABSTRACT

A solid-state circuit providing a succession of similar short voltage rise time sparks for automotive engine ignition purposes during the period the timing breaker of the ignition system is open to replace the single spark per ignition of conventional automotive ignition systems.

United States Patent Inventors Glenn B. Warren 1361 Myron $1.. Schenectady, 11.11. 12309; William R. Scboltz, 207 Wymnn SL, Scotia,

NY. 12302 Appl. No. 862,167 Filed Sept. 30, 1969 Patented July 27, 1971 SOLID-STATE MULTISPARK IGNITION 1 Claim, 1 Drawing Fig.

us. or 31s/2o9sc, 315/209 01), 317/79 1111. c1 11051137/02, H05b 41/36 Field ofSeanch 317/79, 96, 80; 315/206, 209, 223; 431/264 [56] References Cited UNITED STATES PATENTS 3,174,075 3/1965 Jukes 315/206 3,184,638 5/1965 Wood 315/206 3312860 4/1967 Sturm 1 315/223 3,424,944 1/1969 Nilssen 315/209 Primary ExaminerVolodymar Y. Mayewsky Attorney-Kane, Dalsimer, Kane, Sullivan and Kurucz ABSTRACT: A so1id-state circuit providing a succession of similar short voltage rise time sparks for automotive engine ignition purposes during the period the timing breaker of the ignition system is open to replace the single spark per ignition of conventional automotive ignition systems.

&

SOLID-STATE MULTISPARK IGNITION BACKGROUND OF THE INVENTION In the currently pending application of Glenn B. Warren entitled MULTISPARK IGNITION SYSTEM filed June I8, 1969, now US. Pat. No. 3,520,132, the advantages of multispark ignition over single spark ignition are set forth. This application also discloses a method of obtaining multispark ignition wherein a motor driven commutator wheel is utilized to provide the desired multispark frequency. Although such mechanical and electromechanical components as that of the pending application operate properly, they require periodic maintenance, repair, and replacement of worn parts to operate within the degree of accuracy necessary for smooth engine performance. Further, such mechanical components tend to be adversely affected by weather and climate conditions.

SUMMARY OF THE INVENTION It is, therefore, the principal object of the present invention to provide a solid-state control circuit adapted to be utilized with a conventional automotive ignition system for purposes of providing a series of short duration parks during each ignition period.

The basic principle employed here is to provide a solid-state circuit and devices whereby the rise in voltage on the main capacitor in the circuit of a capacitor discharge type ignition system as it is recharged will serve when it reaches a predetermined level to cause a switch (usually an SCR) in the circuit to ground to conduct and so ground" the capacitor and complete the capacitor-ignition coil primary winding circuit. This will permit the capacitor to discharge through the primary winding of the ignition coil and so induce a sparking voltage in the ignition coil secondary. Hence, when the switch (SCR) is reopened in the usual manner by the reverse surge of current in the primary coil-capacitor circuit the capacitor can be recharged by the power supply, and will again discharge when the voltage in the charge of the capacitor is again built up, thus giving a series of sparks. The frequency of such sparks is determined by the characteristics of the several components of the system.

These and other beneficial objects and advantages are attained in accordance with the present invention in one embodiment by providing a solid-state circuit including a power supply connected to one terminal of a capacitor, the other terminal of which is connected to the primary winding of the ignition system ignition coil. First and second Zener diodes connected in series extend between the junction of the power supply and capacitor and the gating terminal of a first silicon controlled rectifier. The first SCR and a second SCR connected in series therewith extend between ground and the junction of the capacitor and power supply and, hence, when conductive, enable the capacitor to discharge across the primary winding of the induction coil which is also grounded. The gating terminal of the second SCR is connected to the nongrounded terminal of the engine timer breaker-points. When the points are opened, the second SCR will become gated and when the Zeners conduct, the first SCR will be gated. When both SCRs are gated, the capacitor will discharge across the ignition coil primary winding, inducing a high voltage surge in the coil secondary winding. The Zeners conduct when the charge on the capacitor builds up to their breakdown voltage and stop conducting when the capacitor charge falls below this voltage. Thus, when the breaker-points open, the capacitor will cyclically discharge across the primary winding and then rebuild up, inducing corresponding high voltage surges in the secondary winding producing a series of sparks across the spark plug gap connected in series to the secondary winding. Other. type solid-state devices might be used in place of the Zeners to provide the triggering of the SCR when the proper voltage buildup on the capacitor is reached.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawing is a schematic representation of the solid-state multispark ignition system control circuit of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT sistor 14 to the nongrounded contact 16 of breaker-points 18.

Thus, when the ignition switch is on and the breaker-points are closed, current from the battery will flow through resistor 14 and the breaker-points to ground. A voltage multiplier 20 is provided which serves to step up the output voltage of battery 10 (usually l2 volts) to between approximately 300 and 375 volts DC. The voltage multiplier power supply is connected to the junction of switch 12 and resistor 14 and one terminal of capacitor 22. Thus, when breaker-points 18 are closed, the gating terminal of SCR 34 is grounded and the SCR is open so that the voltage multiplier power supply serves to charge capacitor 22. The other terminal of capacitor 22 is connected to one end of the primary winding 24 of ignition coil 26. The other end of winding 24 is grounded.

If multiplier 20 is not designed so that it can have a large voltage drop when the high voltage output is short circuited upon the SCR conducting, an inductance, resistor or both may be required in the position of box 20 to protect the circuit from overload. On the other hand, if the design and the components of multiplier 20 are selected to withstand such surge, no protective components in box 20' are required.

First and second Zener diodes 28 and 30, in series, are con- I nected through resistor 31 to the junction of multiplier 20 and capacitor 22. The cathode of diode 30 is connected to the gating terminal of a first silicon controlled rectifier 32. The anode of SCR 32 is also connected to the junction of multiplier 20 and capacitor 22 and the cathode of the first SCR 32 is connected to the anode of a second SCR 34, the cathode of which is grounded. The gating terminal of the second SCR 34 is connected through resistor 36 to the junction of nongrounded breaker contact 16 and resistor 14 and through resistor 38 to ground. Thus, when the breaker-points are closed by a cam 19, the gating terminal of SCR 34 will be grounded and the SCR will not conduct. However, when the breaker contacts are separated by the timing cam 19 driven by the engine shaft the SCR 34 will receive a gating signal from battery 10 through resistors 14 and 36, thereby turning SCR 34 on and the series of sparks are then started. Also, as stated above, when the breaker-points are closed, capacitor 22 will charge from voltage multiplier 20. When the charge on capacitor 22 reaches the breakdown voltage of the Zener diodes, and if SCR 34 is conducting, the diodes will conduct and transmit a gating signal to SCR 32, rendering SCR 32 conductive. That is, if the breaker-points are open, the gating terminal of SLR 34 will receive a voltage from the common junction of resistors l4 and 38 and cause SCR 34 to conduct. With both SCRs conductive, capacitor 22 will discharge through the primary winding 24 of coil 26, thereby inducing a high voltage surge across the secondary winding 40 of the ignition coil. This high voltage surge is transmitted through distributor 42 to the appropriate spark plug 44 producing a spark across the gap of the plug.

The reverse surge of current through SCR 32 from the primary winding 24 of the coil turns OFF the SCR, thereby enabling the capacitor to recharge and again build up to the breakdown voltage of the Zeners. This process will repeat over and over as long as the breaker-points 18 remain open so that SCR 34 remains gated. For optimum automotive applical. A solid-state automotive ignition system adapted to pro- I vide a series of relatively short duration short voltage rise time sparks for ignition purposes during each successive ignition period comprising:

a voltage source having a power terminal and a ground terminal; an ignition coil having primary and secondary windings with one end of each grounded; an ignition switch, voltage multiplier and capacitor connected respectively in series between the power terminal of said voltage source and the nongrounded end of said primary winding of said ignition coil;

a spark plug having spark electrodes connected in series between the secondary of said ignition coil and ground, said secondary winding being coupled to said primary winding for producing a spark upon the discharge of said capacitor across said primary winding;

engine timer means including a pair of cam operated breaker-points, the separation of which defines the beginning of said ignition period, said breaker points having one grounded contact and one nongrounded contact connected to the juncture between said ignition switch and said voltage multiplier;

first and second SCRs with ,the anode of said first SCR connected to the junction between said voltage multiplier and said capacitor, the anode of said second SCR connected to the cathode of said first SCR and the cathode of I 

1. A solid-state automotive ignition system adapted to provide a series of relatively short duration short voltage rise time sparks for ignition purposes during each successive ignition period comprising: a voltage source having a power terminal and a ground terminal; an ignition coil having primary and secondary windings with one end of each grounded; an ignition switch, voltage multiplier and capacitor connected respectively in series between the power terminal of said voltage source and the nongrounded end of said primary winding of said ignition coil; a spark plug having spark electrodes connected in series between the secondary of said ignition coil and ground, said secondary winding being coupled to said primary winding for producing a spark upon the discharge of said capacitor across said primary winding; engine timer means including a pair of cam operated breakerpoints, the separation of which defines the beginning of said ignition period, said breaker points having one grounded contact and one nongrounded contact connected to the juncture between said ignition switch and said voltage multiplier; first and second SCRs with the anode of said first SCR connected to the junction between said voltage multiplier and said capacitor, the anode of said second SCR connected to the cathode of said first SCR and the cathode of said second SCR grounded; diode means having a cathode connected to the junction between said capacitor and said voltage multiplier and an anode connected to the gate of said first SCR so arranged as to conduct when the charge on said capacitor builds up to a predetermined voltage level; and the gate of said second SCR connected to the nongrounded breaker-points of said engine timer means providing said second SCR with conducting signals from said voltage source upon the separation of the contacts of said breaker. 